Gender slant on hygiene hypothesis could explain skewed disease rates

The “hygiene hypothesis” suggests that increased hygiene and sanitation is linked to higher rates of asthma, allergies and autoimmune disorders. Now, one researcher says the differences in boys’ and girls’ play-styles could explain why women are at greater risk of asthma, allergies, and autoimmune disorders such as Crohn’s disease and rheumatoid arthritis.

Oregon State University’s Sharyn Clough thinks autoimmune disease researchers need to dig deeper to explore gender’s effect. In her new study, published in the journal Social Science & Medicine, she notes that autoimmune diseases strike women three times more than men. With the disease lupus, nine times as many women are affected as men. There is no consensus on why these gender differences exist.

Clough’s study details a variety of sociological and anthropological research showing that our society socializes young girls very differently from young boys. In particular, how girls are generally kept from getting dirty compared to boys.

“Girls tend to be dressed more in clothing that is not supposed to get dirty, girls tend to play indoors more than boys, and girl’s playtime is more often supervised by parents,” explained Clough. “There is a significant difference in the types and amounts of germs that girls and boys are exposed to, and this might explain some of the health differences we find between women and men.”

Clough believes the link between hygiene, gender and disease is not just a fluke. “We are just now beginning to learn about the complex relationship between bacteria and health,” she said. “More than 90 percent of the cells in our body are microbial rather than human. It would seem that we have co-evolved with bacteria.”

The hygiene hypothesis is well-supported and Clough hopes her study will prompt epidemiologists and clinicians involved in autoimmune research to go back and examine their data through the lens of gender. In the meantime, she says more outdoor time for kids is good – even if that means they get a little dirty. “Getting everyone, both boys and girls, from an early age to be outdoors as much as possible is something I can get behind,” she concluded.